With packages moored below or beneath the surface of water, it is desirable to have a remotely controlled release mechanism for disengaging the packages from their moorings thus allowing them to rise to the surface for retrieval or to sink below toward the bottom. Such apparatus have commonly been used with subsea data collecting instruments, especially where such instruments are anchored at significant depths. Such instruments are typically connected to or integrated with a flotation device. At shallow depths, the flotation device may be kept at the surface for easy retrieval by surface vessels. When the submerged package is at more significant depths or it is desired that the submerged package not be easily sighted at the water surface, it is typical to secure the package and flotation device completely below the water by attaching it to a mooring via an intermediate, acoustically triggered, release.
Prior release mechanisms have been remotely triggered with acoustic communications devices using narrowly limited and discrete sets of signals. For instance, a typical device might accommodate a few discrete frequencies that, when detected by the release mechanism, cause it to disengage from the mooring apparatus and allow the disconnected package to float to the surface for retrieval.
Another desirable feature to have with underwater packages is the ability to transfer large amounts of data between them and the surface while such packages remain submerged. There are currently available advanced apparatus and methods for communicating large amounts of voice and other data through water, facilitated by what are typically referred to as underwater modems. These underwater modems generally provide the same functionality as those commonly used for global network communications across telephone, microwave, radio and other mediums. Underwater modems currently provide a dynamic means for high-rate data transfer between land, above-water and underwater vessels, and instruments such as those used for collecting information about undersea conditions.
Thus, current practice is to use multiple communications links and protocols from surface to sub sea units to retrieve data from undersea packages, communicate with their various components, and issue commands to release mechanisms. These practices are redundant and result in inefficient and costly apparatus comprised of multiple battery/power sources and communications instruments both below and above the surface.
Consequently, there is a need to be able to efficiently and effectively acquire data from submerged instrument packages and also release them from their underwater moorings for retrieval, and it is a primary object of the present invention to address this need.
Other objects of the invention will, in part, appear hereinafter and, in part, be obvious when the following detailed description is read in connection with the drawings.